Electronic packages, such as electronic control modules, generally contain electronic devices, such as surface mount components, typically having fabricated electrical integrated circuitry (IC). The circuitry conducts electrical current which, in turn, generates thermal energy (i.e. heat) within the electronic package. The heat may build-up to an elevated temperature within the package. Excessive heat in electronic devices and other components within an electronic package may lead to adverse effects including electrical circuit failure. Thus, it is desirable to dissipate heat away from some electronic packages.
Many electronic packages employ semiconductor devices in the form of surface mount components soldered or otherwise connected to the surface of a substrate. Examples of surface mount components include flip chips and insulated gate bi-polar transistor (IGBT) chips. Some conventional techniques for dissipating thermal energy away from the electronic package employ a thermally conductive heat sink supported in contact with the package, held in place via clamps or directly mounting the heat sink onto a printed circuit board. One approach for conducting heat from a flip chip semiconductor device is disclosed in U.S. Pat. No. 6,180,436, the entire disclosure of which is hereby incorporated herein by reference. The aforementioned approach employs a flip chip mounted on a flexible substrate, having a rigid heat-conductive pedestal brought into thermal contact with one surface of the flip chip, and a biasing member. The biasing member biases the substrate against the flip chip to maintain thermal contact between the chip and the heat-conductive pedestal member.
Other heat sink assemblies employ a rigid circuit board mounted to a metal back plate which forms a case of a housing. Because of various tolerance issues and since there generally is no compliance built into the packaging, an inconsistent bond-line typically exists between the semiconductor IC devices and the rigid heat sink pedestals. The tolerance stack-ups of the various electronic devices makes it difficult to maintain a consistent thin thermal joint between the back side of the IC devices and the respective pedestals on the heat sink cover. The existence of a thin thermal joint is generally necessary for low thermal resistance of the IC devices to the heat sink material of the housing. Some compliance generally must be designed into the assembly at the expense of added parts and cost to accommodate for the tolerance stack-ups.
While conventional electronic package assemblies generally suffice to dissipate some of the thermal energy (heat) away from the semiconductor device(s), many packages do not offer optimal heat dissipation. The rigid pedestals in the heat sink cover of some conventional packages typically are not kept in optimal thermal conductive contact with the semiconductor device(s), thereby resulting in less than optimal thermal conductivity and inefficient heat transfer. Other conventional packages typically require added parts and costs in an attempt to improve the thermal contact.
Accordingly, it is therefore desirable to provide for a cost-affordable electronic package and method of dissipating thermal energy (heat) away from the semiconductor device in an optimal and efficient manner.